Lead wire detector



June 10, 1 958 J. B. LINDSAY LEAD WIRE DETECTOR Filedemls, -1955 mwwle United States Patent LEAD Winn nnrncron .lames B. Lindsay, Milburn, N. J., assignor to Kahle Engineering Co., North Bergen, N. J., a copartnership Application February 16, 1955, Serial No. 438,666

3 Claims. (Cl. Z50-429) `This invention relates to the manufacture of vacuum tubes and lamps and more specifically concerns a lead Wire detector for use in stem molding and forming apparatus.

ln the fabrication of vacuum tubes and other similar structures the operative elements of the tubes are mounted on a glass stem or a button having lead wires extending therethrough for connection of the elements to external circuits. Each tube requires a certain number and disposition of lead wires and the omission or misplacement of one or more of the lead Wires renders the finished tube inoperative. Accordingly this invention provides an improved method and means for checking the number and arrangement `of lead wires in a jig prior to the formation of the stem. lf desired the apparatus may be utilized to actuate lead wire ejection means to remove all of the lead wires from the jig in the event one or more of the wires are missing or damaged or should the wires be improperly arranged. The invention is particularly applicable to automatic apparatus of the type generally used for the manufacture of tube stems and provides a positive and dependable detector that avoids mechanical contactors, feelers and the like.

Another object of the invention resides in the pro- Vision of a dependable, relatively inexpensive lead wire detector that can be arranged to check not only the presence of the lead wires but also their length and diameter within certain tolerances.

Still another object of the invention resides in the provision of a lead wire detector wherein the lead wires are not required to mechanically actuate detecting means that may damage or deform the wires or wherein a wire may become jammed in the detector and thus render the entire fabricating1 apparatus inoperative.

A still further object of the invention resides in the provision of a new and improved lead wire detector.

The above and other objects and advantages of the invention will become apparent from the following description and accompanying drawings forming part of this application. f

In the drawings:

Fig. l is a perspective view of stern fabricating apparatus embodying the invention;

Fig. 2 is a cross sectional view of a lead wire detector in accordance with the invention; and

Fig. 3 is a cross sectional View of the embodiment of the invention shown in Fig. 2 taken along the line 3-3 thereof and including associated electric circuits for actuating lead wire removal apparatus.

Referring now to the gures and more specifically to Fig. l of the drawings, 1t) denotes a rotatable turret having a plurality of stem holding fixtures 12 on which the tube stems are to be formed. Above the stem holders are wire feeding mechanism 14 and stem forming fixture 16 and between them is disposed a lead wire detector 18 in accordance `with the invention. The wire feeding mechanism 14, stem forming xture 16 and the detector rice 18 are spaced apart and form individual stations for the l performance of the stem forming operations. Since the procedure for manufacturing a stem is Well known only those portions of the stem forming machine have been illustrated that are necessary to show the application of the invention thereto.

. As each of the stem holding fixtures 12 are moved lfrom station to station by periodic rotation of the turret lil, lead wires 26 are fed by means-of tubes 21 at the loading station into a ixture 14 for insertion in and support by a plurality of openings 22 in the iixture 12 as shown in Fig. 2. While the lead wires may be.of any suitable shape, a common form of wires have cylindrical portions 23 which lit into slots 22 and smaller diameter cylindrical portions 24 extending therefrom to mount the elements of the completed vacuum tube or bulb. In the event one of the feed tubes 21 becomes clogged or otherwise feeds improperly, or in the event one or more of the lead wires 2t) fails to seat properly in the jig 12, a defective stem` or base will result. To avoid this situation, detecting means 18 is provided at the next successive station and may be supported independently for motion toward and away from the fixtures 12 or carried by a horizontal bracket 25 attached to and movable by the loading means 14. A

Thus as the loading means 14 is reciprocated in the operation of the apparatus to move into contact with a fixture 1.2 for loading, the succeeding xture is aligned with a detecting device i8 which surrounds the lead wires 2i? as previously described to determine whether or not all of the wires are in position yand properly arranged. In the event one or more of the wires 20 are missing, the detector will function to actuate a motor-blower 26 terminating in the air nozzle 26 which functions to remove all of the wires 2t) from the center fixture 12 (Fig.

l) as the turret is moved to advance each fixture to the next station.

The detecting apparatus 18 is shown in cross section in Fig. 2 and one embodiment of a circuit diagram is illustrated in Fig. 3 along with a transverse section of the structure shown in Fig. 2. Referring now to these iigures, the detector comprises an elongated cylindrical body 27 having a central opening 28 therein.V Body 27 is preferably made of a non-magnetic material. such as a nonmagnetic metal or a vitreous material to prevent its attractingwires 26. At the lower end of the body there are a series of longitudinal lead wire receiving openings 2% heaving a ilared portion 3) to facilitate the alignment of the lead wires 20 with the openings 29 and prevent accidental bending or damaging of the wires. In addition to these vertically disposed openings 29 there are a series of transverse openings 32 extending clear through the body 27 and intersecting the openings 29 as shown more clearly in Fig. 3. While these openings may be of any suitable size and conguration, they are preferably made slightly narrower than the cylindrical portion 24 of the lead wires 20 While the dimension in the vertical direction may exceed this value. Thus with this arrangement we have one opening 32 intersecting each of the openings il?, with the 32 being controlled in size so that the disposition of a lead wire portion 24 within the opening 29 will completely interrupt the transmission of light through the opening 32.

The detecting means in this embodiment of the invention comprises a plurality of photocells 33 suitably secured to the lower end of the body 27 and arranged to receive light from the openings 32. While these photocells may be of any suitable shape or form, it is of course preferable to provide a suitably encased photocell that will be shielded from ambient light and protected from dirt, dust and other foreign matter that may interfere with its operation. The commonly known 1F42 is one type of end-on photocell suitable for this use.

Within the central portion of the body is an elongated cylindrical member 34 having means on its lower end thereof for receiving an energy radiating source such as the incandescent lamp 35 or other light producing means. In this embodiment of the invention, a lamp having a screw threaded base 36 is provided and adapted to be threadably received in the lower end of the rod or cylinder 34. An insulated wire 37 extends centrally of the rod or cylinder 34 and contacts the center terminal 36' of the lamp base 36 (Eig. 3). The entire lamp assembly is held in place by a set screw 38 or other suitable means that facilitates its vertical adjustment within the center opening 28 of the housing 27. Thus the application of a suitable source of energy to the metallic member 34 and the lead wire 37 will illuminate the lamp 35. The lamp 35 is aligned with the openings 32 so that light will be transmitted to the photocells 33 in the absence of lead wires 2i? in the openings 29.

The photocells 33 are connected in parallel one with the others by a shielded wire 33 and this wire together with the wires 39 and lil for illuminating the lamp 35 may be formed into a single cable 41. It is apparent from the description thus far that as the detecting device 18 is lowered over a s'et of lead wires 2l) in a fixture 12 the presence of wires in all of the openings 29 will interrupt the transmission of light from the lamp 35 through their associated radially disposed opening 32 so that light will not be detected by the associated photocells 33. However, in the event a wire is missing or has been bent out of line with the detector 1S, the transverse opening 32 associated with the vertically disposed opening 29 will not be interrupted and light will be detected by the associated photocell. In this case a signal will be generated that will actuate the blower 26 and deliver air from the nozzle 26' in the manner now to be described.

The photocells are actuated by the light generated by lamp which is connected with voltage supply conductors i4 and 45 by means of a voltage reducing transformer 4.6 having a secondary 46 and primary 46". T he conductors 44 and 45 are provided with suitable terminals 42 and 43 for connection to a power supply. While the lamp 35 may be of any type, one that will produce light fluctuations in accordance with the alternating current energyl applied to the terminals 42 and 43 will facilitate amplification of the light signal. If desired a gaseous type lamp such as a neon lamp or the like may be used for this purpose.

The photocells 33 are illustrated as being connected in parallel and to a suitable alternating current amplifier 47 and the output of the amplifier in the case of the alternating light source preferably includes rectifying means to supply direct current for the actuation of a relay 4S. With this arrangement, if one or more of the photocells 33 is energized by reason of the omission or deformation of a lead wire 2@ a signal will be impressed upon the amplifier 47 and an output signal generated to actuate the relay 48.

In the operation of this device the blower 26 must be actuated only during the time turret l@ is being indexed since the lead wires Ztl, if improperly arranged or if one or more of them are missing or deformed, must be removed prior to arrival of the fixture 12 at the next successive station 16. The operation of the blower is accomplished in this embodiment of the invention by a rotatable cam 5l! having cam surfaces 51 and 52 thereon and cooperating cam actuated switch assemblies 53 and 54. In order to prevent operation of the amplifier 47 and relay 48 during periods other than when detector 18 is in the lowered position and enveloping the lead wires 20, a switch 25' is disposed below and operated by the transverse supporting bracket 25 carrying the detector 18. As will be shown, this switch controls the illumination of the lamp 35 so that the lamp is lighted only when the detector 18 is in lowered position and the bracket 25 moves the switch 25 into its on position.

The cam follower assembly 53 is provided with a roller 53 adapted to ride on the upper surface of the rotatable cam 5d under the action of the spring 53a. The assembly is pivoted at 55 and carries on its outer end a pair of cooperating contacts 56 and 57 for the purpose of electrically locking the relay 4S in the closed position. The cam follower 54 disposed on the underside of the cam 50 for cooperation with the cam surface 52 is provided with a roller 54 held against the underside of cam 50 by a spring 53. This cam follower is pivoted at 59 and carries a pair of contacts 60 and 61 for completing the electric circuit to the blower 26 as the turret 10 is being transported.

Referring now to the circuit diagram shown in Fig. 3, when the loading and detecting stations 14 and 13 are lowered, the bracket 25 actuates a switch 25 to energize the lamp 35 as previously described. In the event a lead wire 2h is missing one of the photocells 33 will respond to the presence of light through the associated transverse passage 32 and actuate the amplifier 47. This will produce an electric signal on the leads 61 and 62 to actuate and close the relay 48. Since the contacts 56 and 57 of the cam assembly 53 are in a normally closed position, a circuit is closed from the battery 63, terminal 64, lead wiresv 65 and 62 to the relay 4S and then via the lead wires 6l. and 66, relay contacts '67 and 68, cam follower contacts 56 and 5'7 through the lead 69 and terminal 70 back to the battery 63. This holding circuit will now maintain the relay l in the closed position until released by contacts 56 and 57 of cam follower 53.

After a predetermined time required for the performance of the stern fabricating operations, the heads 14, 16, l and others are all raised for indexing of the turret lil. As the turret moves it rotates the cam 59 and moves the cain surface 52 into contact with the cam follower assembly 54.. This action closes the contacts 6) and 6l associated therewith and completes a circuit from the power source terminals to the blower 26 in the following manner: leads 43, 71 to the cam follower contact 61, Contact 6i) and lead 72 to the blower 26 and then through lead '73, relay contacts 74- and 75 and leads 76 and Ltd to the power terminal 42. Since the relay is in a closed position, the blo-wer 26 will now discharge air from the nozzle 26. As the cam Si) continues to move the cam surface 52 rides beneath the cam follower assembly 54 and operates the blower for a period long enough to remove the lead wires 2@ from a fixture 12, whereupon the contacts f6@ and 61 of the cam follower 5d are then opened to turn off the blower. After this has occurred the cam surface 5l engages the roller 53 of the cam follower 53 to momentarily open the associated contacts 56 and 57. This breaks Athe locking circuit on relay 43 and permits it to open. Note that during this `operation the bracket 25 is in a raised position and a switch 2,5 has been opened to interrupt the ow of energy to die lamp immediately after the interruption of the locking circuit and opening of the relay 43 the turret il? arrives at its next successive indexing position, whereupon the stern forming apparatus such as the stations la, r6 and l are lowered to repeat the stem forming process. Thus the blower 26 is actuated only during' movement of tue turret liti and the detecting as- Seznbly is reset for the next detecting operation prior to the termination of these indexing motions.

For convenience a battery 63 has been illustrated to provide relay locking current at the terminals 6a and 7d.

lf desired this locking current may be obtained from any suitable source and may be either alternating current or direct current. Since it is necessary to merely hold the relay in the closed position for a predetermined time interval, the relay t8 maybe a time delay relay or suitable time delay circuits may be employed in the amplitier 47 for holding the relay in the closed position for the desired length of time. in the latter case the cam assembly 53 could be eliminated.

In the illustrated embodiment of the invention the radial openings 32 that function to conduct light from the lamp 35 to the photocells 33 are disposed near the lower ends of the openings 25. ln the event it is desired to utilize this photoelectric system for the purpose of determining Whether or not all of the pins or lead wires 20 are of proper length, the transverse openings 32 may be disposed so they intersect the upper ends of the lead wires 20. In this case if a lead wire is too short it will admit light to its associated photocell in the same manner as though it were missing altogether. lt is also important to note that the Width of the openings 32 are preferably slightly narrower than the diameter of the pins or lead wires 20 to be detected. In this way should a lead wire be slightly bent or of too small a diameter, light will pass about the lead wire and actuate the photocell in the manner previously described. Thus if a lead wire is too small in diameter, it will cause the removal of all of the pins from its Xture 12 in the same manner as though it were either too short or missing altogether.

While only one embodiment of the invention has been illustrated and described, it is apparent that modications, alterations or changes may be made without departing from the true scope and spirit thereof.

Having thus described my invention, I claim:

1. Lead wire detecting apparatus comprising an elongated body part having a. central opening terminating in at least one end face of said body and a plurality of longitudinal openings surrounding said central opening for receiving said lead wires, a plurality of light conducting 6 v passageways extending from the outer surface of said body part .and communicating with said central opening, each of said passageways intersecting one of said longitudinal openings, a light source in said central opening and light responsive means associated with the outer end of said passageways and responsive to detect the presence of lead wires in said longitudinal openings.

2. The detecting apparatus as claimed in claim 1 in which said passageways have a width approximately equal to the width of the normal lead wires being detected whereby lead wires which are narrower than said lead wires will allow light to pass to said light responsive means.

3.'The detecting apparatus as claimed in claim 1 in which said passageways intersect said longitudinal openings at a point spaced a predetermined distance from the said end face whereby lead wires penetrating into said longitudinal openings less than said predetermined distance permit light from said light source to reach said light responsive means.

References Cited in the file of this patent UNITED STATES PATENTS 1,921,862 Bickley Aug. 8, 1933 2,012,186 Fihe Aug. 20, 1935 2,085,671 Powers June 29, 1937 2,233,788 Lewin Mar. 4, 1941 2,244,826 Cox June 10, 1941 2,286,170 Heiland June 9, 1942 2,315,287 Holloway Mar. 30, 1943 2,437,071 Cahusac Mar. 2, 1948 2,438,825 Roth Mar. 30, 1948 2,691,246 Roeber Oct. 12, 1954 

